Medical devices often include telemetry circuitry for wirelessly communicating with other devices or monitors. For example, an implantable medical device typically includes a telemetry module capable of bidirectional communication with an external programmer or home monitor for programming and adjusting operating parameters in the implanted device and for retrieving data from the implanted device.
In the past, implantable medical device telemetry systems required a programming head including an antenna to be held directly over the implanted device. Advances made in telemetry systems allow wireless communication over a distance of a few meters, sometimes referred to as “distance telemetry”, without the use of a programming head. Telemetry modules incorporated in implantable devices are designed to operate using a relatively low current to prevent excessive battery drain which would shorten the longevity of the implanted device. In the external programmer, home monitor or other device communicating with the implanted device, the telemetry module needs to be sensitive to the desired signals but can be susceptible to interference both within the communication bandwidth and outside the communication bandwidth. Undesired interference signals can block or impair receiving operations of a low dynamic range receiver. It is desirable to improve the tolerance of low dynamic range telemetry systems to interference signals in medical device systems.